The present invention is a reactor that removes noxious vehicle engine exhausts, such as smoke, soot particles, unburned hydrocarbons, carbon monoxide, and nitrogen oxides (NO.sub.x) prior to release to the atmosphere. The final product released to the atmosphere contains only water vapor, carbon dioxide, and clean exhaust gases. It accomplishes this by recovering the exhaust heat from internal combustion engines; utilizing the exhaust emissions as fuels to generate additional combustion energy; applying thermal radiation enhancement, impinging heat transfer and energy trapping to achieve a high temperature environment of up to 800.degree. C., or above; and using state-of-the-art insulation materials to minimize energy losses to the surroundings.
Health and environmental concerns with automobile emissions have resulted in increasingly stringent and restrictive vehicle emission standards for hydrocarbons, carbon monoxide, NO.sub.x, and particulates such as soot and smog. Soot, or smoke, is basically a carbon particle from heating of lubricants or from agglomeration and dehydrogenation of hydrocarbon fuels during combustion processes. Smog is basically a mixture of soot, water vapor, and unburnt fuel. Soot-laden black smoke is readily observed being emitted from exhaust pipes of large trucks powered by diesel engines. However, when filters are used to reduce soot and smoke emissions, some studies show that engine particulate filters or traps collect only 60-90% of the particles. The retained particles progressively block the flow passage and increase back pressures, thus causing reduced engine output power and fuel economy.
For typical gasoline engines, the engine outlet temperature is in the range of 320.degree.-370.degree. C. and the temperature of the exhaust after leaving the catalytic converter is in the range of 540.degree.-650.degree. C. For gasoline engines, oxygen content in the exhaust is about 1% because of incomplete combustion. Unburned hydrocarbons and carbon monoxide in the presence of 1% oxygen can be oxidized at temperatures in excess of 300.degree. C. to 350.degree. C. Sustaining temperatures in excess of 400.degree. C. before gasoline engine exhaust is released to the atmosphere will reduce emissions of unburned hydrocarbons, carbon monoxide, and NO.sub.x.
The maximum engine outlet temperature from diesel engines can be as high as 800.degree. C. The oxygen content at exhaust is about 10-12% because of turbocharging at an air/fuel ratio as high as 25% excess air. Soot oxidizes slowly at 300.degree. C. and rapidly at 400.degree. C. in air or gas mixtures containing 10% oxygen. Also soot burns from diesel exhaust filters if temperatures in the vicinity of 540.degree. C. are reached in the presence of adequate oxygen. Therefore, sustaining diesel engines exhaust temperatures in excess of 400.degree. C. with an oxygen content of about 10% will enhance oxidation of soot particles, thereby reducing releases of soot to the atmosphere.
A recognized problem for catalytic converters in use with gasoline engines as reported by Ashley in Mechanical Engineering in November 1994 is that from 60% to 85% of the hydrocarbon emissions are generated during the first 200 seconds following cold startup. This is because catalytic converters cannot efficiently remove these pollutants until they attain their effective operating temperature of 300.degree. C. or greater.